774 PROCEEDINGS OF SECTION II. 



the cost of the pumping', because, as the refuse must he col- 

 lected and disposed of, and as it is universally admitted that, 

 in reference to a considerable part of it, burning- is the only 

 proper disposal, and should be done whether the heat pro- 

 -^'nced by such burning l)e utilized or not, the steam produced 

 may be said to cost nothing in the way of fuel. 



We are now in a position to consider what I have said I 

 thought to be the only other practicable way of sufficiently 

 purifying the sewage before discharge iu the case of a seaside 

 town — that is, by some iron process. One of these processes 

 — Electrolysis — is based on the oxidation of the organic matter 

 in the sewage by the electric current acting on iron plates 

 placed in shoots leading from the sewers into the settling- 

 tanks, and so arranged that all the sewage must come into 

 contact with the iron dissolved from the plates. This iron in 

 ])recipitating, as ferric oxide, mechanically carries down with it 

 the suspended matters, and at the same time gives off oxygen 

 to the organic matters in solution. The result is, that after 

 the precipitation has taken place the water is free from 

 suspended matters, and has lost from 57 to 87 per cent, of 

 the albumenoid ammonia the sewage contained — a degree of 

 purity that is quite sufficient for a tidal river, as the electro- 

 lytic action has also rendered the water practically im- 

 putrescible. I suppose that after the experiments on a large 

 scale, made by Mr. Webster, the inventor of the process, at 

 Crossness, with the London sewage, we must consider that 

 electrolysis has entered into its practicable stage. But I will 

 not occupy time by further consideration of it, as there is 

 another i)"on process that practically has the same effect, from 

 analagous action, and at a very much less cost. 



This other process consists in the employment of ferozone 

 as a precipitant and purifier of the sewage. According to an 

 analysis made by Sir Henry Roscoe, ferozone consists of — 



Ferrous sulphate 26*64 



Aluminium sulphate 2*19 



Calcium sulphate 3'30 



Magnesium sulphate 5'17 



Combined water 8*20 



Moisture 24-14 



Silica 11 '35 



Magnetic oxide of iron 19*01 



100*00 



